how do solar panels work

How do solar panels work?

In its simplest terms, solar panels produce voltage (energy) from light; this is where you may see the phrase ‘solar PV’. PV stands for PhotoVoltaic, which translates to: energy from light. In this case, this light energy is from the sun.

As the sun shines on the panels, semiconductors turn light into electrical energy by absorbing and then managing the movement of electrons. This movement of electrons creates an electrical current. 

This electricity is then further refined and worked by components in the solar system to make sure it’s suitable for use in your home and importantly, matches the type of electricity that is supplied to your home or commercial property by your energy supplier.

A common myth around solar panels is that they rely on direct sunlight to produce power. Sure, the greater the intensity of the light, the more power is produced. However, standard daylight alone will still allow panels to produce power, meaning even on overcast days you can still power your home with solar energy. 

Types of solar systems

There are 3 different types of solar systems, each with their own use cases offering flexibility to suit your, your property and your energy consumption needs. 

Traditional string system (Super Sunny solar package)

Let's first look at our Super Sunny Solar package. Our Super Sunny package is a traditional solar setup, but what exactly does this mean?

In short it is designed for customers that do not have any permanent shade on their roof. This could be obstructions such as trees, chimneys, or other objects that will permanently cast a shadow.

This is due to how the different panels work together if they are shaded. In this type of system, all panels reduce their output to match the lowest production panel. For example, in the example below if one of the panels was covered with shade throughout the day, this causes the panel’s production to drop to 15%, for the period the shade was present. With this system all other panels would match the shaded panels production and drop to 15%.

So this is our traditional package. You should now be able to understand why it's called super sunny because the roof always needs to be super sunny with no permanent shade in order to make the most of the panels and the power of the sun.

Optimised system (shade optimised system)

Although there are a lot of houses that may have completely unobstructed roof aspects, there are equally just as many that will have shadows cast on them throughout the day. This is where our optimised system comes in.

Our shade optimised solution is perfect for any customer that has shade on their roof. Using the same scenario as before, one of the panels is being shaded by a tree. With the standard solar system, all panels would be impacted and system production reduced to match the output of the shaded panel. This is where our shade optimised package really shines (excuse the pun). With our shade optimised package, each of the solar panels has an optimiser attached to it (the black boxes in the below image underneath the solar panels). In simple terms, this makes the panel a smart panel with the optimiser allowing the system to sense that some of the panels are affected by shade, but not all of them. This then allows the panels unaffected by the shade to continue producing as much power as possible. 

Pretty clever right? But that's not all. Using a shade optimised SolarEdge package, customers can view solar panel production in real time, not as an overall system, but by panel. You can see each panel on your roof and exactly how much energy each of them is producing. Really handy to check that everything is working properly, and give some great insights. 

So that's our two systems. Super Sunny is our traditional solar system like most are on the market and our shade optimised package really does take solar power to the next level, making sure that as much of the sun's power is being captured wherever possible in all conditions.

Microinverter/Enphase system

There is also a third type of system which is not offered by Egg but we’ve included it here to give you the full picture of your solar options. A microinverter/Enphase solar system has similarities to the optimised system, in the way that it can adapt power for each solar panel. Whereas the optimised system has a power optimiser connected to each panel the microinverter/Enphase system has a microinverter for each panel (the black box connected to the panels in the below image). This means the microinverters convert energy individually from each of the solar panels. 

This is not offered by Egg as a solution due to its limited benefits and the pricing differences when compared to our shade optimised systems (a microinverter system is more expensive than a standard string system). It has more equipment on the roof than a traditional system and limits the number of battery storage systems that are available to users.

Already know which one you want to go with? Great! Head to our solar build journey to get your bespoke quote and see how much you can save on your energy bills.

What is battery storage and do I need it?

Solar panels will only generate energy during daylight hours. A smart way to maximise the return on investment from your solar panel system, a home battery stores any extra solar power that you generate, so that you can use it later – even after the sun goes down.

An average of 50% of your solar power goes unused and is usually sold to and self-consumed by the grid. With a battery, that ‘lost’ energy is stored for later use.

What’s more, you can even store energy from the grid during the night when energy is cheaper by being less in demand – and, with smart scheduling, monitor, manage and schedule its charge.

Find out more about the battery storage, the benefits and the options available to you with our comprehensive battery guide or shop egg’s solar and battery solutions.

With Solar PV, can I come off grid?

To come off grid, you’d need a sufficient solar system and battery storage to meet your household demand. 

If you do not have battery storage installed, you cannot use the electricity generated by your solar panels during non-daylight hours. Even with battery storage, you are reliant on the battery having a large enough capacity to power the house when your solar panels aren't producing electricity. The array would also have to be large enough to power the house during daylight hours and recharge the batteries.

How long will solar panels last?

Most solar panels have a 25-year performance guarantee, but with regular maintenance and servicing there’s no reason they shouldn’t last 25 years and beyond! At egg, we use high quality components to ensure maximum lifespan. 

The initial installation and equipment costs are recovered over several years before becoming profitable, but saving money on electricity over that period isn’t the only benefit. Recent research shows solar panels can increase the resale value of your home, with green home improvements boosting house prices by on average, by up to 15%.

Does my house need to be south facing for solar panels?

South facing roofs are generally more effective in terms of power generation, but that doesn’t mean other orientations aren’t suitable for solar. Assuming a south-facing PV array is 100% rating, a south east / south west facing roof could still yield 94% of that power, whilst an east or west facing roof could yield around 80% of that power.

Whilst most people may consider a north facing roof, or anything other than south to not be suitable for solar panels, that simply isn’t true. There are multiple factors which determine how effective solar panels can be, roof direction is one of them, however shading and roof pitch also need to be considered.

How do I know if my property is suitable for solar? 

A bespoke quote from egg will gather data on your property, its roof and any shading. We then use specialist software to map the sun’s path over your property and calculate how much energy could be produced based on the number of panels that could fit on your roof. We’ll then compare this against your energy consumption to give you a detailed financial breakdown of the costs involved and the potential savings.

Speak to one of our solar experts today for your bespoke solar quote. 

Whilst cost savings is generally the biggest reason to have solar installed, reducing your reliance on non-renewable energy resources and protecting yourself against unstable energy prices are also important factors.

I have shade on my roof can I still get solar panels? 

Fortunately shade is not a blocker for solar panels to work on a home or commercial property, with ‘shade optimised’ systems available which are able to maximise the output of a solar system, even when there is shading in place.

A traditional system will drastically reduce the overall output of the system if any single panel is shaded. This means that even the smallest amount of shading can have enormous impacts on the overall system production.

However, shade optimised systems bypass any shaded panels and allow the remainder of the array to continue producing as much electricity as possible. When the shading is gone, the previously shaded panels then start producing electricity again. All controlled automatically by the optimisation systems, to produce the most power possible from the daylight that is available.

Follow our simple Solar package journey to find the right solution for you and speak to one of our solar experts about your personal solar needs and requirements. 

Do solar panels work in winter?

In short, yes! Solar panel systems continue to generate electricity during the winter months, although their efficiency may be reduced compared to the rest of the year due to a reduction in daylight hours and a change in the angle of the sun.

Solar panels can operate on daylight and do not require direct sunlight to produce power. Of course the more direct sunlight you have, the more power will be produced, but you can still benefit from solar power production in the winter.

Solar during a power cut?

For safety reasons solar panels are designed to shut down if there is a grid outage. Unless your property can ‘island’ itself, your system cannot produce power during a power cut. When a solar system "islands itself," it continues to supply the solar panel generated power to the house and, often, a battery storage system, even when the grid is down. 

Installing a Tesla Powerwall with Backup Gateway, or equivalent system can automatically island your property to allow power production to continue during a grid outage.

Why can’t I have solar?

Before you head over to our solar build journey to start your solar and storage transition, make sure you qualify.

Reasons why solar may not be an option:

• You have a weak or damaged roof that will require additional work prior to installation

• You live in a conservation area or a listed building. Approval will be required prior to installation.

• You’re unable to obtain DNO approval for the required system size. DNO is the District Network Operator, the distributor providing power to your home and responsible for maintaining the power lines. Please note: this is different to your energy supplier such as EDF, OVO etc. The Application for a DNO approval is something that we at Egg handle on your behalf. 

Reasons why it may not be beneficial to have solar installed:

• You have a north facing roof 

• There isn’t enough roof space

• Your roof is heavily shaded throughout the day

• You are not the homeowner

What our solar expert says:

“Solar panels maximise the potential of sunlight, essentially turning it into free electricity. This electricity can power your home, be stored for later use, charge your electric vehicle or even earn you money for selling it back to the grid!

When choosing your solar panels, the individual output power and efficiency of a panel should be considered. While individual panel level production may not seem to affect your savings over a month, consider 16 of those panels on your roof, over the next 25 years. A small difference in production figures at panel-level could mean a big difference over the life of the system.”

Chris Pickford - energy expert at egg